On Saturday 30 July 2016 12:43:55 Gene Heskett wrote: > On Saturday 30 July 2016 08:10:20 Erik Christiansen wrote: > > On 23.07.16 18:03, Erik Christiansen wrote: > > > Point 4 on the page appears to make clear that the 12v must be > > > turned on before the high voltage power; there are no interlock > > > relays in this basic unit, and it's BYO fan, too. > > > > Gene: Here's a HEADS UP!: > > My Chinglish interpreter skills were lacking. What that word soup > > apparently means is that the 12v must have a short rise time, to > > kick the MOSFETs into oscillation, thereby keeping the magic smoke > > in. > > So are mine, and I've spent 40 years of my working life translating > the service manuals that go with Sony's high price broadcast gear. > The J.A.Pan company manages to do understandably well at English. > > But the Chinese and Indians (despite most Indians speaking English > with clipped Brit accents), neither can write it well. > > > Here's a chap who's bought one, putting it through its paces: > > > > https://www.youtube.com/watch?v=gNL4H5fC6AY > > > > Nothing is lost if you skip from 5 min to 20 min in the recording. > > > > Armed with that info, one unit might suffice, especially if the > > junkbox includes reasonably equivalent spare MOSFETs. > > Such as those in the common atx power supply? > > Anyway, it seems they need a hard switched power supply, so turn it on > first, then hard switch it to the unit. > > My problem is sourceing a suitable supply. I'd assume if I use A2, > which is air hardening steel, that if I wanted full length hardening, > I could simply pass a long piece thru it, paced to obtain the temp > needed, that I would wind up with a full length hardened piece. But > that generates a couple questions. > > 1. Is the austenitic state hot enough for A2? > Couple answers from the practical machinist blog. This on is no, the heat range for A2 is 1725 to 1750F. Thats a fairly tight spec that would need to be verified with a pyrometer, something thats not on my tool shelves.
> 2. Does A2 need a faster cooling profile than I'd get by doing the > slow transport like this: Again no, A2 needs to "soak" at that temp for 20 to 30 minutes in order for the chemical changes to do their job. So it must be protected from the oxygen in the air, either by a controlled atmosphere, or by wrapping in SS foil, or possibly by dipping it in a flux powder once its hot enough to melt and make a coating of flux to block the air. That also demands a water cooling setup for the coil if its going to be excited for the several hours it might take to do a 6" long piece given the needed soaking time. > I can visualize a mill setup with a clamp on the cold end to to move > the other end into the coil, which would be mounted on the head > somehow so that the x axis motion would carry it into and thru the > coil, until such motion has brought the far end thru the coil and out > far enough to cool, then adding an identical gripper to the end that > has been thru the coil, and removing the gripper that was holding it > when the x axis motion started, so that the part would continue its > motion thru the coil until the full length has been so heated. I can > see a couple heavy wooden blocks with pipe sections mounted at upward > angles, the first one being pulled out after the second one is slid in > to hold it from the hot end, maintaining a generally centered position > that holds the part sufficiently level, all while the slow x motion is > carrying it thru the coil. > > So the question then is do I need an air blast nozzle to effect a > quicker cooling temp profile, located just beyond the heated portion > so as to cool it faster? I have an air pump from a defunct soldering > station that could supply that air in variable amounts. > > So, what do the experienced heat treaters here have to say about such > a kludgey setup for onesies or twosies? So it gets more complex, and costly. I now have a picture of an inert liner for the coil, with small holes in the ends to let the material pass thru, and which is flooded with a low flow of mig gas, which is 25% carbon dioxide, and 75% argon. I get the thought that the carbon dioxide might raise the surface hardness since I learned 60 years ago that you can make any hardness you want out of coat hangers and a smith wrench just by adjusting the flame, and that 25% is the equ of running a 1/4" "feather" in the torch flame that touches the puddle. If that is a concern, then pure argon can be had, just bring money as its at least 2x the mig gas. That gas, for that length of time will triple the cost until you realize that the gas flow, once the "chamber" is flushed of air, can be turned down to almost zip. Just enough to keep the air out. 2 or 3 cc's a minute maybe, so maybe a 50% rise in operating costs would cover it. ====================================================================== Now, I know that some read this list on gmane, but the gmane owner is considering shutting it down, so those of you who are not subscribed should consider subscribing to these lists. That story was on /. in this past week. Thanks everybody. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
